Exam-style question
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A particle of mass 4 kg has resultant force 16 N. Find the acceleration.
- A.4 m s^-2
- B.8
- C.0
- D.4 m s^-2 distractor 3
Model answer
What a good answer should say
- The correct answer is 4 m s^-2.
This answer is tied to the objective: R4 Understand and use Newton's third law; use equilibrium of forces on a particle and motion in a straight line, restricted to forces in two perpendicular directions or simple two-dimensional vector cases; apply to smooth pulleys and connected particles; resolve forces in two dimensions; use equilibrium of a particle under coplanar forces..
Explanation
Why this works
Use the explanation to connect the worked answer back to R4 Understand and use Newton's third law; use equilibrium of forces on a particle and motion in a straight line, restricted to forces in two perpendicular directions or simple two-dimensional vector cases; apply to smooth pulleys and connected particles; resolve forces in two dimensions; use equilibrium of a particle under coplanar forces..
Trace the calculation before choosing. The verified method for Newton's third law and equilibrium gives 4 m s^-2; no later explanation is allowed to change that value.
Maths method check
- Topic focus: Mechanics.
- Question style: practice.
- Reasoning demand: analysis.
- Check the operation, notation, units, and final answer form against the question before moving on.
Common mistake
No common mistake is linked to this question yet.